Glow tube control system



Feb. 11, 1936. D. APPLE BAUM GLOW TUBE CONTROL SYSTEM Filed Dec. 14, 1931 lllllhlllllllt- IIIIIIIIIIIIIII'I'IIII ,z'nregzfor fiaw'a A o o/eaum 194% w A f/or'n ey Patented Feb. 11, 1936 UNITED, STATES? PATENT o JFicE' 13 Claims.

This invention relates to a source of illumination the intensity of which can be controlled accurately and instantaneously in accordance with electrical impulses Such devices in general are now in common use for various purposes. For example, in sound recording on film, it is common to use a glow tube which is intended to respond to sound waves. This is done by first transforming these waves into electrical current impulses, as by a microphone or the like, and these impulses in turn are caused ,to aflecta varying ionization of the gas in the tube. This varying ionization in turn causes a corresponding illumination of the tube. This illumination can then be used in a well-known way torecord the impulseston an appropriate light sensitive medium. In television also such glow tubes are used for forming an image at the receiving end.

Such systems, while practicable, have inherent disadvantages. The light variations, which must be rapid, have a tendency to lag behind the current variations, probably due to partial neutralization of the space charge in the tube by the production of negative ions. Furthermore, the

gas viscosity effect which slows down the ions, also enhances the lag. To overcome these effects, very high voltages across the tube electrodes were necessary, even when a supplemental reservoir of ions is used.

It is one of the objects of my invention to avoid the gas viscosity efiect with its attendant deceleration of the electron motion; and at the same time to obviate the need of destructive high voltages.

This object is attained by providing a source of electrons which is separate from the glow tube but which can be used to excite it by causing the electrons to pass through the gas of the glow tube.

It is thus another object of my inventionto provide a compound tube, in which the two compartments are sealed against gas exchange, but so arranged that electrons generated in one compartment can pass into the other compartillumination by ionization.

stood that this detailed description is not to be 1 taken in a limiting sense,since the scope of my invention is best defined by the appended claims.

Referring to the drawing:

Figure 1 is a diagram of a system for producing variable illumination and embodying my 15 invention; and

Fig. 2 is a modification thereof.

In Fig. 1 there is shown a multiple compartment tube II which can be sealed in any appropriate manner. This tube can conveniently be made from glass, and can be thus readily provided with conductors sealed through-the walls to connect to internal electrodes as will be hereinafter described. The tube It is divided into two non-communicating compartments l2 and I3 by the aid of a thin membrane M. This membrane can be of glass or metal; and preferably it can be formed of very thin aluminum.

In the present instance, the right hand com partment I2 provides a space which is highly evacuated and in which electrons are produced. The left hand compartment l3 on the other hand, has a gaseous content at subatmospheric pres-' sure. This content is acted upon by the electrons that pass through the window or membrane ll, and is caused to luminesce.

As a practical example, compartment l3 can have a filling of one or a mixture of noble monatomic gases, such as helium or neon, at almost any convenient pressure of the order of glow 40 discharge tube pressures. of course, the advantage of keeping the pressure low is that the window M can be made very thin as there is thus no great stress placed upon it; and accordingly, it can be made quite pervious to electrons and yet tight against gas interchange.

' Electrons created in compartment I2 are directed against the window M. If they travel with suflicient velocity, they pass through the window and cause the gas in chamber ii to luminesce. It is suflicient to note that the intensity of illumination is a function of the speed of the electrons, which can be controlled in accordance with the impulses corresponding to speech or sight in a manner to be described.

heated as by current supplied by a battery IS.

A variable resistance I! can be used to adJust the filament temperature by varying the heating current. If desired, a focusing tube I8 01 conducting material can surround the filament and can be appropriately supported. Such focusing tubes are well known and may be biased negativeiy with respect to the cathodeor they may be completelyinsulated, in which case electrons accumulate thereon until the tube assumes a sufilcient negative potential with respect to the cathode to deflect any electrons traveling towards the tube. In this manner, the emitted electrons are urged more rapidly towards the anode. As a rule such tubes have a circular cross section and are mounted with the cathode-positioned inside the tube and withthe axis of 'the tube parallel to a line connecting the cathode and the anode. The anode can be the metallic. wall l4, supplemented by a tubular member IS in electrical contacttherewith. This tube shields thewalls of the tube from electron bombardment. When the potential difference between cathode l 5 and anode l4l9 is sufiiciently high, the electrons instead of being all captured on the anode,

will pass through into compartment l3. Preferably when no impulses are being received, the potential difierence is maintained at an intermediate value, causing an-intermediate illumination in chamber l3. Then as impulses of alternate signs or directions are received,'the illumination is reduced when the impulses-are in one direction and increased when they are in the opposite direction. A potential difference of the order of radio B batteries is required for biasing the space in the compartment l2 so as to produce sufilcient velocity of the electron stream to affect an intermediate illumination in chamber l3.

The anode-cathode circuit thus includes cathode IS, a center tap 20 on a potentiometer 2| bridging the cathode IS, a biasing source of potential, such as a battery 22, of 3000 volts or higher, and having its negative side toward the cathode l5, a secondary winding 23 of a transformer 24, supplying the impulses that algebraically add potential differences to that of battery 22, a variable resistor 25 for adjusting the biasing potential, and lastly, anode structure ll-IQ. The source of impulses in this instance is represented by element 26 supplying primary winding 21 of transformer 24 with current varying in accordance with the impulses. This source 26 can be a microphone or a television receiver or the like.

As the impulses vary in intensity, the voltage impressed across the electrodes varies in accordance therewith, whereby the speed and number of the emitted electrons are correspondingly varied and accordingly the illumination of chainber l3. Hereinafter, for the sake of brevity, the

term intensity of electron flow is intended to example to affect a film for talking motion Since it may happen that some of the positive ions in chamber i3 do not recombine but become strays, there it may be provided if desired an electrode 28 which can collect the negative ions; the positive ions flowing towindow i4. However, such an electrode can be omitted. This electrode is connected by an external circuit to window I through a source 29 of electrical potential, and a variable resistance 30, for providing a closed'circuit for these ions. The source 29 can be abattery of low potential, such .as ten volts, insuflicient by itself-to produce any ionization, and used only for the purpose of impressing an attracting potential on electrode 28.

In Fig. 2 substantially the same scheme is shown as in .Fig. 1. Here the tube 3| has the two compartments 32 and 33 respectively corresponding to chambers 12 and I3. In this case .however, the window 34 is shown as reinforced by a grid 35; and the tube 36 is placed close tothe walls of tube 3|. The collecting'of the stray ions may be accomplished by the aid of a pair of spaced needle electrodes 31, 38. These electrodes are'in circuit with a low voltage secondary coil 39 of transformer 24, which coil is a substitute for battery 29 of Fig. 1. Here again the voltage impressed across electrodes 3", 38 is toolow to cause any glow, all glow being produced by the electrons that pass through the window 34 and grid 35. The collection of ions in this form is synchronous with the impression of impulses on the electron discharging means.

I claim: I 1. In adeyice for producing illumination varying rapidly in accordance with electrical impulses, means definingan evacuated, space, a

cathode and an anode in the spme, means enclosing an ionizable gas atmosphere adjacent the space and separated from it by an electron pervious window, means producing a steady space ing rapidly in accordance with electrical impulses, means defining an evacuated space, a cathode and an anode in the space, said means including an electron pervious window, supplemental means enclosing an ionizable gas atmosphere adjacent the space and separated from it by the electron pervious window, means for varying the space charge between thecathode and anode to cause electrons to be directed toward the window, to produce a glow varying in accordance with the charge, and means for collecting a ,stray electrons in the gas.

3. The combination as set forth in claim 2, in ,,which the means for collecting stray ions is a pair of electrodes and an external circuit between the electrodes, said circuit including a source of potential insufiicient to ionize the gas.

4. The combination as set forth in claim 2, in which the means for collecting stray ions is a pair of electrodes and an'external circuit between the electrodes, said circuit including a source of potential insufiicient to ionize the gas and varying in synchrony with the impulses.

5. In combination, means forming a compartment enclosing a gas that luminesces in accordance with the ionization thereof, a portion of the wall of the compartment being pervious to electrons, and means for causing the gas to luminesce variably, comprising wallsdefining a space on the other side of the pervious portion, a hot cathode in said space, means whereby-electrons from the cathode are directed toward the pervious portion, and supplementary means for rapidly varying the intensity of the electron flow, at audio frequencies.

6. In combination, means forming a compartment enclosing a gas that luminesces in accordance with the ionization thereof, a portion of the wall of the compartment being pervious to electrons, and means for causing the gas to luminesce variably, comprising means defining a space on the other side of the pervious portion, an electron emitting electrode in said space, said pervious portion contributing to form an anode in said space, and a circuit connecting said portion and the electrode, including a source of variable electrical impulses.

7. The process of producing varying illumination in accordance with electrical impulses, which comprises emitting electrons in a vacuum from a source of electrons, varying the intensity of the electron flow in accordance with electrical impulses, and transmitting the electrons from the space where they are emitted into a body of gas that can luminesce upon ionization.

8. In a device for producing varying illumination, means defining an evacuated space, a hot cathode in the space, means forming an anode surface in the space, said means having at least a portion thereof which is pervious to electrons,

means for rapidly varying the intensity of the electron stream, at audio frequencies, and means enclosing a gas on the other side of the pervious portion, which gas is capable of luminescing when ionized, and in accordance with the intensity of the ionization. v

9. In a device for producing rapidly varying illumination, a vessel, an electron pervious partition in said vessel, forming a pair of compart ments, one of said compartments beingjevacuated, the other having an ionizable gas filling, an anode and cathode in the evacuated compartment, for producing a stream of electrons, at least some of which pass into the gas, said gas being free of any ionization field, whereby the ionization of the gas is due solely to the action of the electrons, and means for rapidly varying the character of the electron stream.

10. The combination as set forth in claim 9, in which the partition is a thin metallic member and forms an electrode in the gas compartment.

11. In a device for producing rapidly varying illumination, varying in conformity with rapidly varying electrical impulses, a vessel, an electron pervious partition in said vessel, forming a pair of compartments, one of said compartments being evacuated, the other having an ionizable gas filling, an anode and a cathode in the evacuated compartment for producing a stream of electrons in said compartment, at least some of which pass into the gas to cause it to ionize solely by the action of said electrons, and means for varying the intensity of said stream in accordance with said impulses.

12. In a device for producing rapidly varying illumination, varying in conformity with rapidly varying electrical impulses, a vessel, an electron pervious partition in said vessel, forming a pair of compartments, one of said compartments being evacuated, the other having an ionizable gas filling, an anode and a cathode in the evacuated compartment for producing a stream of electrons in said compartment, at least some of which pass into the gas to cause it to ionize solely by the action of said electrons, and means for varying the velocity of the electron stream in accordance with said impulses.

13. The combination as set forth in claim 12, in which the velocity varying means is a device for varying the intensity of the electric field in the evacuated space.

DAVID APPLEBAUM. 

